John Terry's position as England captain came under greater scrutiny on Tuesday night after Hammersmith and Fulham police launched a formal investigation into allegations that he racially abused Anton Ferdinand during Chelsea's defeat at Queens Park Rangers last month.

The Metropolitan police had spent the previous week assessing a complaint that was emailed by a member of the public 24 hours after the game at Loftus Road. Confirmation that police were starting an inquiry that could yet end in criminal proceedings was delivered shortly before Chelsea were held to a surprise 1-1 Champions League draw against Genk on Tuesday night. It was a game in which Terry was an unused substitute and it was marred by chants from sections of the travelling support.

Some among the 1,100 visiting fans were heard chorusing: "We know what you are, we know what you are. Anton Ferdinand, we know what you are." The Chelsea manager, André Villas-Boas, was unaware of the chanting at the time and declined to comment when it was related to him but a spokesman for the Premier League club later condemned the fans' reaction. "It was wholly inappropriate and we do not condone it," he said.

The Football Association's inquiry into the incident at Loftus Road is ongoing; Terry and Ferdinand have been interviewed and witness statements have been collected by the body's disciplinary and governance unit.

There had been hopes that the matter would be resolved this week, before the announcement on Sunday of Fabio Capello's England squad for friendlies against Spain and Sweden. It now seems the issue is likely to be hanging over Terry if he captains the national side for the games at Wembley.

There had been no suggestion that the 30-year-old would be omitted from the national squad as a result of being the subject of the FA inquiry, and there is nothing to prevent him from being picked now the police have launched their investigation. Capello's intention to pick an experimental squad, however, will give him a convenient reason for omitting Terry if he is minded to do so.

The FA seemed to confirm on Tuesday night that it would not rule on the matter without knowing if the police intended to bring charges against the defender. It said: "The Metropolitan police has contacted the FA to make us further aware of their investigation into the matter. Due to this it would be inappropriate for the FA to comment until the police have completed their own inquiries."

The Met are not working to any set timeframe and are likely to seek interviews with those involved. Terry admits that he used offensive words but says he shouted them as a denial, having been under the impression that Ferdinand had accused him of making a racist remark. He welcomed the FA's inquiry as an opportunity to clear his name.

Ferdinand, who was targeted with racist abuse on Twitter on Tuesday, broke his public silence on the matter this week saying he had ""very strong feelings" on the issue and was confident the FA would undertake a "very thorough inquiry" into the matter. He has submitted his written testimony to the disciplinary and governance unit.